Flat display devices comprise a thin planar display panel such as a plasma display panel or a field emission display panel or the like.
For example, a plasma display panel has a structure in which a pair of a front substrate and a rear substrate are disposed facing one another in parallel and the periphery of a discharge space between the front and rear substrates is sealed.
A reflective-type AC-type plasma display panel has a constitution in which a plurality of row electrode pairs that perform surface discharge (display discharge) on the inner face of the front substrate and a dielectric layer that covers the row electrode pairs are formed, in which, on the inner face side of the rear substrate facing the front substrate, column electrodes that are disposed in a direction orthogonal to the row electrode pairs and perform selective discharge with respect to one row electrode of the row electrode pairs and a column electrode protection layer that covers the column electrodes are formed, and in which a barrier wall that divides the discharge space into each of the discharge cells is formed between the front and rear substrates, phosphor layers color-divided into three primary colors red, green, and blue respectively being formed side by side in that order in each of the discharge cells.
In the conventional flat display device mentioned above, a front filter (panel protection plate) disposed in front of the flat display panel is constituted by sticking an external light anti-reflection sheet and a film that blocks electromagnetic waves and infrared waves generated by the flat display panel onto a glass substrate.
In addition, a technology where, in an LED display device having a plurality of LED elements, reflection by the LED elements is prevented by sticking a light-blocking louver film to the surface of the LED elements and irradiating the LED elements with external light in a direction intersecting the thickness direction is known. Here, the louver film is stuck to the surface of the LED elements by means of an adhesive material (See Patent Document 1).
In addition, a plasma display panel resin sheet capable of transmitting rectilinear light whereon transparent areas and dark-colored areas are formed alternately in the sheet surface direction is known. The transparent areas and dark-colored areas are each orthogonal or oblique with respect to the sheet surface and inclined in the form of layers. A technology that stacks a plasma display panel resin sheet, a bandpass filter and an electromagnetic wave shield layer is also known (See Patent Document 2).
In addition, in the case of a microlens array sheet in which a first material layer and a second material layer which has a smaller refractive index than that of the first material layer are sandwiched between two parallel planes and a micro unit lens that functions as a lens due to the fact that the interface between the first and second material layers forms a concave and/or convex shape is disposed in a planar state, a microlens array sheet formed by mounting at least a convex apex area of the first material layer of the micro unit lens on a transparent substrate via a pressure-sensitive adhesive or bonding adhesive such as an acrylic resin and, if necessary, via a spacer, as well as a liquid-crystal display that employs the microlens array sheet are also known (See Patent Document 3).
In addition, a reduction in the number of parts and simplification of the support structure of the flat display panel as well as a lower cost product are achieved by sticking a plastic optical filter integrally to the screen of the flat display panel instead of providing a protective panel made of a conventional glass substrate separately from the flat display panel (See Patent Document 4).    Patent Document 1: Japanese Patent Application Laid Open No. 2000-29406    Patent Document 2: Japanese Patent Application Laid Open No. 2004-295045    Patent Document 3: Japanese Patent Application Laid Open No. H09-127309    Patent Document 4: Japanese Patent Application Laid Open No. 2004-206076
The external light of an indoor light or the like is generally reflected by the screen of a display device that displays an image such as a flat display panel or the like, whereby the problem of black luminance sharpness and deterioration in the contrast on the screen is generated.
In the prior art disclosed by the Patent Documents mentioned above, a sheet or film having a light-absorbing or light-blocking horizontal louver structure comprising a black or dark-colored material is adopted in order to improve the contrast and prevent external light. However, in cases where the viewer views the screen obliquely from above or at a position above the front of the screen, that is, in cases where the viewer views the screen at an inclination to the horizontal line of sight, there is a viewing angle problem that the screen be hardly seen or inconvenient for the viewer.
For example, with a display panel equipped with a sheet that has a black horizontal louver structure, in cases where the screen is viewed with a slope of 45 degrees as shown in FIG. 14, a plurality of louvers cast a shadow and the lower half of the screen cannot be seen. The upper half of the screen cannot be seen in cases where the screen is viewed at an angle of elevation.